Xor sum

#include <iostream>
#include <vector>
using namespace std;

int main() {
    int n_count, q_count;
    cin >> n_count >> q_count;

    vector<int> answers(q_count), n(n_count), prefix(n_count + 1, 0);

    for (int i = 0; i < n_count; i++) {
        cin >> n[i];
    }

    for (int i = 0; i < n_count; i++) {
        prefix[i + 1] = prefix[i] ^ n[i];
    };

    for (int i = 0; i < q_count; i++) {
        int a, b;
        cin >> a >> b;
        answers.push_back(prefix[a - 1] ^ prefix[b]);
    };

    for (int answer : answers) {
        cout << answer << endl;
    };

    return 0;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER